51
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Riddiford LJ, Grutter AJ, Pillsbury T, Stanley M, Reifsnyder Hickey D, Li P, Alem N, Samarth N, Suzuki Y. Understanding Signatures of Emergent Magnetism in Topological Insulator/Ferrite Bilayers. PHYSICAL REVIEW LETTERS 2022; 128:126802. [PMID: 35394317 DOI: 10.1103/physrevlett.128.126802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/21/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
Magnetic insulator-topological insulator heterostructures have been studied in search of chiral edge states via proximity induced magnetism in the topological insulator, but these states have been elusive. We identified MgAl_{0.5}Fe_{1.5}O_{4}/Bi_{2}Se_{3} bilayers for a possible magnetic proximity effect. Electrical transport and polarized neutron reflectometry suggest a proximity effect, but structural data indicate a disordered interface as the origin of the magnetic response. Our results provide a strategy via correlation of microstructure with magnetic data to confirm a magnetic proximity effect.
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Affiliation(s)
- Lauren J Riddiford
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Alexander J Grutter
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Timothy Pillsbury
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Max Stanley
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Danielle Reifsnyder Hickey
- Department of Materials Science, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Peng Li
- Department of Electrical Engineering and Computer Science, Auburn University, Auburn University, Auburn, Alabama 36849, USA
| | - Nasim Alem
- Department of Materials Science, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Nitin Samarth
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yuri Suzuki
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
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52
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Wu Y, Wang W, Pan L, Wang KL. Manipulating Exchange Bias in a Van der Waals Ferromagnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2105266. [PMID: 34910836 DOI: 10.1002/adma.202105266] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 12/01/2021] [Indexed: 06/14/2023]
Abstract
Spintronics applications of thin-film magnets require control and design of specific magnetic properties. Exchange bias, originating from the pinning of spins in a ferromagnet by these of an antiferromagnet, is a part of the highly important elements for spintronics applications. Here, an exchange bias of ≈90 mT in a van der Waals ferromagnet encapsulated by two antiferromagnets at 5 K, the value of which is highly tunable by the field coolings, is reported. The non-antisymmetric dependence of exchange bias on field cooling is explained through considering an uncompensated interfacial magnetic layer of an antiferromagnet with a noncollinear spin texture, and a weak antiferromagnetic order in the oxidized layer, at two ferromagnet/antiferromagnet interfaces. This work opens up new routes toward designing and controlling 2D spintronic devices made of atomically thin van der Waals magnets.
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Affiliation(s)
- Yingying Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Wei Wang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China
| | - Lei Pan
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
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53
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Chakraborty SK, Kundu B, Nayak B, Dash SP, Sahoo PK. Challenges and opportunities in 2D heterostructures for electronic and optoelectronic devices. iScience 2022; 25:103942. [PMID: 35265814 PMCID: PMC8898921 DOI: 10.1016/j.isci.2022.103942] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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54
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Yu S, Tang J, Wang Y, Xu F, Li X, Wang X. Recent advances in two-dimensional ferromagnetism: strain-, doping-, structural- and electric field-engineering toward spintronic applications. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2022; 23:140-160. [PMID: 35185390 PMCID: PMC8856075 DOI: 10.1080/14686996.2022.2030652] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 01/03/2022] [Accepted: 01/09/2022] [Indexed: 05/27/2023]
Abstract
Since the first report on truly two-dimensional (2D) magnetic materials in 2017, a wide variety of merging 2D magnetic materials with unusual physical characteristics have been discovered and thus provide an effective platform for exploring the associated novel 2D spintronic devices, which have been made significant progress in both theoretical and experimental studies. Herein, we make a comprehensive review on the recent scientific endeavors and advances on the various engineering strategies on 2D ferromagnets, such as strain-, doping-, structural- and electric field-engineering, toward practical spintronic applications, including spin tunneling junctions, spin field-effect transistors and spin logic gate, etc. In the last, we discuss on current challenges and future opportunities in this field, which may provide useful guidelines for scientists who are exploring the fundamental physical properties and practical spintronic devices of low-dimensional magnets.
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Affiliation(s)
- Sheng Yu
- Institute of Information Technology, Shenzhen Institute of Information Technology, Shenzhen, China
- Institute for Advanced Study, Shenzhen University, Shenzhen, China
| | - Junyu Tang
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Yu Wang
- Institute for Advanced Study, Shenzhen University, Shenzhen, China
| | - Feixiang Xu
- Institute for Advanced Study, Shenzhen University, Shenzhen, China
| | - Xiaoguang Li
- Institute for Advanced Study, Shenzhen University, Shenzhen, China
| | - Xinzhong Wang
- Institute of Information Technology, Shenzhen Institute of Information Technology, Shenzhen, China
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55
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Geng C, Wang X, Zhang S, Dong Z, Xu B, Zhong C. Prediction of two-dimensional monolayer C2O2Fe with chiral magnetic and ferroelectric orders. Phys Chem Chem Phys 2022; 24:16827-16835. [DOI: 10.1039/d2cp01492k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Low-dimensional multiferroics are highly desired for applications and contain exotic physics properties. Here we predict a two-dimensional material, C2O2Fe monolayer, through Fe intercalation in the graphene oxide monolayer. The crystal...
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56
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Nguyen LAT, Dhakal KP, Lee Y, Choi W, Nguyen TD, Hong C, Luong DH, Kim YM, Kim J, Lee M, Choi T, Heinrich AJ, Kim JH, Lee D, Duong DL, Lee YH. Spin-Selective Hole-Exciton Coupling in a V-Doped WSe 2 Ferromagnetic Semiconductor at Room Temperature. ACS NANO 2021; 15:20267-20277. [PMID: 34807575 DOI: 10.1021/acsnano.1c08375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
While valley polarization with strong Zeeman splitting is the most prominent characteristic of two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors under magnetic fields, enhancement of the Zeeman splitting has been demonstrated by incorporating magnetic dopants into the host materials. Unlike Fe, Mn, and Co, V is a distinctive dopant for ferromagnetic semiconducting properties at room temperature with large Zeeman shifting of band edges. Nevertheless, little known is the excitons interacting with spin-polarized carriers in V-doped TMDs. Here, we report anomalous circularly polarized photoluminescence (CPL) in a V-doped WSe2 monolayer at room temperature. Excitons couple to V-induced spin-polarized holes to generate spin-selective positive trions, leading to differences in the populations of neutral excitons and trions between left and right CPL. Using transient absorption spectroscopy, we elucidate the origin of excitons and trions that are inherently distinct for defect-mediated and impurity-mediated trions. Ferromagnetic characteristics are further confirmed by the significant Zeeman splitting of nanodiamonds deposited on the V-doped WSe2 monolayer.
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Affiliation(s)
- Lan-Anh T Nguyen
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Krishna P Dhakal
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Yuhan Lee
- Department of Physics, Korea University, Seoul 02841, Republic of Korea
| | - Wooseon Choi
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Tuan Dung Nguyen
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Chengyun Hong
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Dinh Hoa Luong
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
| | - Young-Min Kim
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jeongyong Kim
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Myeongwon Lee
- Department of Physics, Korea University, Seoul 02841, Republic of Korea
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Ji-Hee Kim
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Donghun Lee
- Department of Physics, Korea University, Seoul 02841, Republic of Korea
| | - Dinh Loc Duong
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
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57
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Yin ZB, Chen XY, Wang YP, Long MQ. The magnetic proximity effect at the MoS 2/CrI 3interface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:035002. [PMID: 34598164 DOI: 10.1088/1361-648x/ac2c3c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
The vicinity to a two-dimensional magnetic material provides a simple and effective way to break the valley degeneracy of transition-metal dichalcogenides because of the magnetic proximity effect. Based on first-principles calculations, we study the band structure of a MoS2/CrI3van der Waals heterostructure and its manipulation by vertical electric fields. A huge valley splitting of about 19.60 meV, equivalent to an external magnetic fields of about 89.0 T can be generated by an electric field of 0.115 V Å-1. The electric field causes discontinuous changes in the valley splitting. The electric field drives the bands of MoS2across those of CrI3. At the critical electric fields, the interlayer orbital hybridization leads to the energy level repulsion and an abrupt exchange of the band index. We also study the effect of interlayer distance on the valley splitting and observe a more significant electric field modulation. This work deepens our understanding on the interfacial magnetic proximity effect as a result of the orbital hybridization across the van der Waals gap.
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Affiliation(s)
- Zhi-Bo Yin
- School of Physics and Electronics, Hunan Key Laboratory for Super-Micro Structure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha, People's Republic of China
| | - Xiao-Yan Chen
- School of Physics and Electronics, Hunan Key Laboratory for Super-Micro Structure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha, People's Republic of China
| | - Yun-Peng Wang
- School of Physics and Electronics, Hunan Key Laboratory for Super-Micro Structure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha, People's Republic of China
| | - Meng-Qiu Long
- School of Physics and Electronics, Hunan Key Laboratory for Super-Micro Structure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha, People's Republic of China
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58
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Kim SJ, Choi D, Kim KW, Lee KY, Kim DH, Hong S, Suh J, Lee C, Kim SK, Park TE, Koo HC. Interface Engineering of Magnetic Anisotropy in van der Waals Ferromagnet-based Heterostructures. ACS NANO 2021; 15:16395-16403. [PMID: 34608798 DOI: 10.1021/acsnano.1c05790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Interface engineering is an effective approach to tune the magnetic properties of van der Waals (vdW) magnets and their heterostructures. The prerequisites for the practical utilization of vdW magnets and heterostructures are a quantitative analysis of their magnetic anisotropy and the ability to modulate their interfacial properties, which have been challenging to achieve with conventional methods. Here we characterize the magnetic anisotropy of Fe3GeTe2 layers by employing the magnetometric technique based on anomalous Hall measurements and confirm its intrinsic nature. In addition, on the basis of the thickness dependences of the anisotropy field, we identify the interfacial and bulk contributions. Furthermore, we demonstrate that the interfacial anisotropy in Fe3GeTe2-based heterostructures is locally controlled by adjacent layers, leading to the realization of multiple magnetic behaviors in a single channel. This work proposes that the magnetometric technique is a useful platform for investigating the intrinsic properties of vdW magnets and that functional devices can be realized by local interface engineering.
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Affiliation(s)
- Sung Jong Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Dongwon Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
- Display and Nanosystem Laboratory, Department of Electrical Engineering, Korea University, Seoul 02841, Korea
| | - Kyoung-Whan Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Ki-Young Lee
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Duck-Ho Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Seokmin Hong
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Joonki Suh
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Changgu Lee
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Se Kwon Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Tae-Eon Park
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Hyun Cheol Koo
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
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59
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She XC, Zhang RL, Zhao JZ, Qi DX, Zou Y, Peng RW. Tunable valley polarization in Janus WSSe by magnetic proximity coupling to a CrI 3 layer. Phys Chem Chem Phys 2021; 23:18182-18188. [PMID: 34612281 DOI: 10.1039/d1cp02577e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the electronic properties and valley physics of Janus monolayer WSSe on a CrI3 substrate layer based on first-principles calculations. It is shown that the K and K' valley degeneracy can be lifted which leads to valley polarization (VP) in the WSSe due to the magnetic proximity coupling to a magnetic substrate. The magnitude of VP is highly sensitive to the interfacial electronic properties and can be tuned by varying the stacking configurations of the heterostructure. Interestingly, the direction of VP can be altered by manipulating the layer alignment without reversing the magnetism orientation of the magnetic substrate CrI3. We suggest that the hybridization between the bands of WSSe and the substrate plays an important role. Meanwhile, the charge distributions have been mapped out to uncover the microscopic origin of the direction variable VP. In addition, large VP can be achieved by adjusting the interlayer spacing. Our investigations may have potential applications in the design of valleytronic devices.
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Affiliation(s)
- X C She
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
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60
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Yao Y, Zhan X, Sendeku MG, Yu P, Dajan FT, Zhu C, Li N, Wang J, Wang F, Wang Z, He J. Recent progress on emergent two-dimensional magnets and heterostructures. NANOTECHNOLOGY 2021; 32:472001. [PMID: 34315143 DOI: 10.1088/1361-6528/ac17fd] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
Intrinsic two-dimensional (2D) magnetic materials own strong long-range magnetism while their characteristics of the ultrathin thickness and smooth surface provide an ideal platform for manipulating the magnetic properties at 2D limit. This makes them to be potential candidates in various spintronic applications compared to their corresponding bulk counterparts. The discovery of magnetic ordering in 2D CrI3and Gr2Ge2Te6nanostructures stimulated tremendous research interest in both experimental and theoretical studies on various intrinsic magnets at 2D limit. This review gives a comprehensive overview of the recent progress on the emergent 2D magnets and heterostructures. Firstly, several kinds of typical 2D magnetic materials discovered in the last few years and their fabrication methods are summarized in detail. Secondly, the current strategies for manipulating magnetic properties in 2D materials are further discussed. Then, the recent advances on the construction of representative van der Waals magnetic heterostructures and their respective performance are provided. With the hope of motivating the researchers in this area, we finally offered the challenges and outlook on 2D magnetism.
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Affiliation(s)
- Yuyu Yao
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Sino-Danish Center for Education, Beijing 100049, People's Republic of China
| | - Xueying Zhan
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Marshet Getaye Sendeku
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Peng Yu
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Fekadu Tsegaye Dajan
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Chuanchao Zhu
- Institute for Quantum Information & State Key Laboratory of High Performance Computing, National University of Defense Technology, Changsha 410073, People's Republic of China
| | - Ningning Li
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Sino-Danish Center for Education, Beijing 100049, People's Republic of China
| | - Junjun Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Feng Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Zhenxing Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jun He
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
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61
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Tiessen J, Shi J. Nano-chevron quantum dot for spin-qubit applications. NANOSCALE 2021; 13:12659-12668. [PMID: 34477616 DOI: 10.1039/d1nr02842a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We study the theoretical properties of a parabolic hBN/MoS2/hBN heterostructure quantum dot potential generated via electrostatic gates and its interaction with a cobalt nano chevron. We demonstrate that such an example system can undergo electric dipole spin resonance for a single electron isolated to the K' valley within the MoS2 monolayer, and such a system can achieve pi-rotation times of approximately 5.5 ns under the influence of a 20.89 GHz driving field. Our proposed system requires operating conditions easily achievable with current experimental methods and would allow for the all-electrical control of a spin-qubit within an MoS2 device. Our results show that such a system is experimentally feasible and would have comparable properties to that of more traditional silicon based spin-qubits. Furthermore, the design of the device can be applied to other material systems beyond MoS2 and cobalt. In theory, the proposed structure could make use of any 2D material that experiences strong proximity exchange interactions with other magnetic materials, which makes our proposed design highly general.
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Affiliation(s)
- John Tiessen
- Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
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62
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Sierra JF, Fabian J, Kawakami RK, Roche S, Valenzuela SO. Van der Waals heterostructures for spintronics and opto-spintronics. NATURE NANOTECHNOLOGY 2021; 16:856-868. [PMID: 34282312 DOI: 10.1038/s41565-021-00936-x] [Citation(s) in RCA: 107] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 06/03/2021] [Indexed: 06/13/2023]
Abstract
The large variety of 2D materials and their co-integration in van der Waals heterostructures enable innovative device engineering. In addition, their atomically thin nature promotes the design of artificial materials by proximity effects that originate from short-range interactions. Such a designer approach is particularly compelling for spintronics, which typically harnesses functionalities from thin layers of magnetic and non-magnetic materials and the interfaces between them. Here we provide an overview of recent progress in 2D spintronics and opto-spintronics using van der Waals heterostructures. After an introduction to the forefront of spin transport research, we highlight the unique spin-related phenomena arising from spin-orbit and magnetic proximity effects. We further describe the ability to create multifunctional hybrid heterostructures based on van der Waals materials, combining spin, valley and excitonic degrees of freedom. We end with an outlook on perspectives and challenges for the design and production of ultracompact all-2D spin devices and their potential applications in conventional and quantum technologies.
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Affiliation(s)
- Juan F Sierra
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
| | - Jaroslav Fabian
- Institute for Theoretical Physics, University of Regensburg, Regensburg, Germany
| | | | - Stephan Roche
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Sergio O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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63
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Wang K, Zhou W, Cheng Y, Zhang M, Wang H, Zhang G. Magnetic order-dependent phonon properties in 2D magnet CrI 3. NANOSCALE 2021; 13:10882-10890. [PMID: 34125128 DOI: 10.1039/d1nr00820j] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We carried out a systematic theoretical study on how spin affects the phononic properties of CrI3 monolayers. We find that the frequencies of two infrared-active (IR) modes are significantly influenced by the magnetic configuration. Thus an IR spectrum may be applied to identify the magnetic order by utilizing the spin-lattice correlation. The thermal expansion coefficients are 2.21, 3.35 and -5.58 × 10-6 K-1 for ferromagnetic (FM), antiferromagnetic (AFM) and paramagnetic (PM) phases at 30 K, because of the competition between the modes with negative and positive Grüneisen constants. Furthermore, the lattice thermal conductivity is also sensitive to the magnetic phase, which is attributed to the spin-dependent lattice anharmonicity. Our results provide fundamental insights into the spin-lattice coupling and clarify the potential of a spintronic monolayer as a thermal switching device for active heat flow control.
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Affiliation(s)
- Ke Wang
- Xidian University, No. 2 Taibai Road, Xi'an, Shaanxi Province 710071, China.
| | - WuXing Zhou
- Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China
| | - Yuan Cheng
- Monash Suzhou Research Institute, Suzhou 215123, China
| | - Min Zhang
- Xidian University, No. 2 Taibai Road, Xi'an, Shaanxi Province 710071, China.
| | - Hai Wang
- Xidian University, No. 2 Taibai Road, Xi'an, Shaanxi Province 710071, China.
| | - Gang Zhang
- Institute of High Performance Computing, A*STAR, 138632, Singapore.
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64
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Ju H, Lee Y, Kim KT, Choi IH, Roh CJ, Son S, Park P, Kim JH, Jung TS, Kim JH, Kim KH, Park JG, Lee JS. Possible Persistence of Multiferroic Order down to Bilayer Limit of van der Waals Material NiI 2. NANO LETTERS 2021; 21:5126-5132. [PMID: 34096728 DOI: 10.1021/acs.nanolett.1c01095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Realizing a state of matter in two dimensions has repeatedly proven a novel route of discovering new physical phenomena. Van der Waals (vdW) materials have been at the center of these now extensive research activities. They offer a natural way of producing a monolayer of matter simply by mechanical exfoliation. This work demonstrates that the possible multiferroic state with coexisting antiferromagnetic and ferroelectric orders persists down to the bilayer flake of NiI2. By exploiting the optical second-harmonic generation technique, both magnitude and direction of the ferroelectric order, arising from the cycloidal spin order, are successfully traced. The possible multiferroic state's transition temperature decreases from 58 K for the bulk to about 20 K for the bilayer. Our observation will spur extensive efforts to demonstrate multifunctionality in vdW materials, which have been tried mostly by using heterostructures of singly ferroic ones until now.
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Affiliation(s)
- Hwiin Ju
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Youjin Lee
- Center for Quantum Materials, Seoul National University, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Kwang-Tak Kim
- Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - In Hyeok Choi
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Chang Jae Roh
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Suhan Son
- Center for Quantum Materials, Seoul National University, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Pyeongjae Park
- Center for Quantum Materials, Seoul National University, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Jae Ha Kim
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Taek Sun Jung
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Jae Hoon Kim
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Kee Hoon Kim
- Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
- Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Je-Geun Park
- Center for Quantum Materials, Seoul National University, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Jong Seok Lee
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
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65
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Kezilebieke S, Silveira OJ, Huda MN, Vaňo V, Aapro M, Ganguli SC, Lahtinen J, Mansell R, van Dijken S, Foster AS, Liljeroth P. Electronic and Magnetic Characterization of Epitaxial CrBr 3 Monolayers on a Superconducting Substrate. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006850. [PMID: 33938604 DOI: 10.1002/adma.202006850] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/22/2020] [Indexed: 05/23/2023]
Abstract
The ability to imprint a given material property to another through a proximity effect in layered 2D materials has opened the way to the creation of designer materials. Here, molecular-beam epitaxy is used for direct synthesis of a superconductor-ferromagnet heterostructure by combining superconducting niobium diselenide (NbSe2 ) with the monolayer ferromagnetic chromium tribromide (CrBr3 ). Using different characterization techniques and density-functional theory calculations, it is confirmed that the CrBr3 monolayer retains its ferromagnetic ordering with a magnetocrystalline anisotropy favoring an out-of-plane spin orientation. Low-temperature scanning tunneling microscopy measurements show a slight reduction of the superconducting gap of NbSe2 and the formation of a vortex lattice on the CrBr3 layer in experiments under an external magnetic field. The results contribute to the broader framework of exploiting proximity effects to realize novel phenomena in 2D heterostructures.
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Affiliation(s)
| | - Orlando J Silveira
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
| | - Md N Huda
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
| | - Viliam Vaňo
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
| | - Markus Aapro
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
| | | | - Jouko Lahtinen
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
| | - Rhodri Mansell
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
| | | | - Adam S Foster
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Peter Liljeroth
- Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
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66
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Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals. Nat Commun 2021; 12:2088. [PMID: 33828083 PMCID: PMC8027870 DOI: 10.1038/s41467-021-22412-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 03/15/2021] [Indexed: 12/04/2022] Open
Abstract
The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery. Systems where both time-reversal symmetry and inversion symmetry are broken can exhibit a magneto-chiral effect; however, this is usually weak. Here, Lan et al demonstrate a significantly enhanced excitonic magnetochiral effect in twisted bilayer tungsten disulphide on a ferromagnetic substrate.
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67
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Wahab DA, Augustin M, Valero SM, Kuang W, Jenkins S, Coronado E, Grigorieva IV, Vera-Marun IJ, Navarro-Moratalla E, Evans RFL, Novoselov KS, Santos EJG. Quantum Rescaling, Domain Metastability, and Hybrid Domain-Walls in 2D CrI 3 Magnets. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2004138. [PMID: 33346397 DOI: 10.1002/adma.202004138] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/07/2020] [Indexed: 06/12/2023]
Abstract
Higher-order exchange interactions and quantum effects are widely known to play an important role in describing the properties of low-dimensional magnetic compounds. Here, the recently discovered 2D van der Waals (vdW) CrI3 is identified as a quantum non-Heisenberg material with properties far beyond an Ising magnet as initially assumed. It is found that biquadratic exchange interactions are essential to quantitatively describe the magnetism of CrI3 but quantum rescaling corrections are required to reproduce its thermal properties. The quantum nature of the heat bath represented by discrete electron-spin and phonon-spin scattering processes induces the formation of spin fluctuations in the low-temperature regime. These fluctuations induce the formation of metastable magnetic domains evolving into a single macroscopic magnetization or even a monodomain over surface areas of a few micrometers. Such domains display hybrid characteristics of Néel and Bloch types with a narrow domain wall width in the range of 3-5 nm. Similar behavior is expected for the majority of 2D vdW magnets where higher-order exchange interactions are appreciable.
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Affiliation(s)
- Dina Abdul Wahab
- School of Mathematics and Physics, Queen's University, Belfast, BT7 1NN, UK
| | - Mathias Augustin
- School of Mathematics and Physics, Queen's University, Belfast, BT7 1NN, UK
| | - Samuel Manas Valero
- Instituto de Ciencia Molecular, Universidad de Valencia, Calle Catedrático José Beltrán 2, 46980, Paterna, Spain
| | - Wenjun Kuang
- School of Physics, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Sarah Jenkins
- Department of Physics, The University of York, York, YO10 5DD, UK
| | - Eugenio Coronado
- Instituto de Ciencia Molecular, Universidad de Valencia, Calle Catedrático José Beltrán 2, 46980, Paterna, Spain
| | - Irina V Grigorieva
- School of Physics, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Ivan J Vera-Marun
- School of Physics, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Efrén Navarro-Moratalla
- Instituto de Ciencia Molecular, Universidad de Valencia, Calle Catedrático José Beltrán 2, 46980, Paterna, Spain
| | | | - Kostya S Novoselov
- School of Physics, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- Department of Material Science & Engineering, National University of Singapore, Block EA, 9 Engineering Drive 1 117575, Singapore
- Chongqing 2D Materials Institute, Liangjiang New Area, Chongqing, 400714, China
| | - Elton J G Santos
- Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, UK
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68
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Liu N, Gallaro CM, Shayan K, Mukherjee A, Kim B, Hone J, Vamivakas N, Strauf S. Antiferromagnetic proximity coupling between semiconductor quantum emitters in WSe 2 and van der Waals ferromagnets. NANOSCALE 2021; 13:832-841. [PMID: 33351877 DOI: 10.1039/d0nr06632j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
van der Waals ferromagnets have gained significant interest due to their unique ability to provide magnetic response even at the level of a few monolayers. Particularly in combination with 2D semiconductors, such as the transition metal dichalcogenide WSe2, one can create heterostructures that feature unique magneto-optical response in the exciton emission through the magnetic proximity effect. Here we use 0D quantum emitters in WSe2 to probe for the ferromagnetic response in heterostructures with Fe3GT and Fe5GT ferromagnets through an all-optical read-out technique that does not require electrodes. The spectrally narrow spin-doublet of the WSe2 quantum emitters allowed to fully resolve the hysteretic magneto-response in the exciton emission, revealing the characteristic signature of both ferro- and antiferromagnetic proximity coupling that originates from the interplay among Fe3GT or Fe5GT, a thin surface oxide, and the spin doublets of the quantum emitters. Our work highlights the utility of 0D quantum emitters for probing interface magnetic dipoles in vdW heterostructures with high precision. The observed hysteretic magneto response in the exciton emission of quantum emitters adds further new degrees of freedom for spin and g-factor manipulation of quantum states.
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Affiliation(s)
- Na Liu
- Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA. and Center for Quantum Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
| | - Cosmo M Gallaro
- Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA. and Center for Quantum Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
| | - Kamran Shayan
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA and Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
| | - Arunabh Mukherjee
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA and Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
| | - Bumho Kim
- Department of Mechanical Engineering, Columbia University, New York 10027, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York 10027, USA
| | - Nick Vamivakas
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA and Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA and Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
| | - Stefan Strauf
- Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA. and Center for Quantum Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
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69
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Chakraborty S, Ravikumar A. Substrate induced electronic phase transitions of CrI[Formula: see text] based van der Waals heterostructures. Sci Rep 2021; 11:198. [PMID: 33420187 PMCID: PMC7794430 DOI: 10.1038/s41598-020-80290-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/14/2020] [Indexed: 11/09/2022] Open
Abstract
We perform first principle density functional theory calculations to predict the substrate induced electronic phase transitions of CrI[Formula: see text] based 2-D heterostructures. We adsorb graphene and MoS[Formula: see text] on novel 2-D ferromagnetic semiconductor-CrI[Formula: see text] and investigate the electronic and magnetic properties of these heterostructures with and without spin orbit coupling (SOC). We find that when strained MoS[Formula: see text] is adsorbed on CrI[Formula: see text], the spin dependent band gap which is a characteristic of CrI[Formula: see text], ceases to remain. The bandgap of the heterostructure reduces drastically ([Formula: see text] 70%) and the heterostructure shows an indirect, spin-independent bandgap of [Formula: see text] 0.5 eV. The heterostructure remains magnetic (with and without SOC) with the magnetic moment localized primarily on CrI[Formula: see text]. Adsorption of graphene on CrI[Formula: see text] induces an electronic phase transition of the subsequent heterostructure to a ferromagnetic metal in both the spin configurations with magnetic moment localized on CrI[Formula: see text]. The SOC induced interaction opens a bandgap of [Formula: see text] 30 meV in the Dirac cone of graphene, which allows us to visualize Chern insulating states without reducing van der Waals gap.
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Affiliation(s)
- Shamik Chakraborty
- Nanoelectronics Research Laboratory, Department of Electronics and Communication Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Bengaluru, 560035 India
| | - Abhilash Ravikumar
- Nanoelectronics Research Laboratory, Department of Electronics and Communication Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Bengaluru, 560035 India
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70
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Meijer MJ, Lucassen J, Duine RA, Swagten HJ, Koopmans B, Lavrijsen R, Guimarães MHD. Chiral Spin Spirals at the Surface of the van der Waals Ferromagnet Fe 3GeTe 2. NANO LETTERS 2020; 20:8563-8568. [PMID: 33238096 PMCID: PMC7729936 DOI: 10.1021/acs.nanolett.0c03111] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/10/2020] [Indexed: 05/28/2023]
Abstract
Topologically protected magnetic structures provide a robust platform for low power consumption devices for computation and data storage. Examples of these structures are skyrmions, chiral domain walls, and spin spirals. Here, we use scanning electron microscopy with polarization analysis to unveil the presence of chiral counterclockwise Néel spin spirals at the surface of a bulk van der Waals ferromagnet Fe3GeTe2 (FGT) at zero magnetic field. These Néel spin spirals survive up to FGT's Curie temperature of TC = 220 K, with little change in the periodicity p = 300 nm of the spin spiral throughout the studied temperature range. The formation of a spin spiral showing counterclockwise rotation strongly suggests the presence of a positive Dzyaloshinskii-Moriya interaction in FGT, which provides the first steps towards the understanding of the magnetic structure of FGT. Our results additionally pave the way for chiral magnetism in van der Waals materials and their heterostructures.
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Affiliation(s)
- Mariëlle J. Meijer
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Juriaan Lucassen
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Rembert A. Duine
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
- Institute
for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE, Utrecht, The Netherlands
| | - Henk J.M. Swagten
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Bert Koopmans
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Reinoud Lavrijsen
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Marcos H. D. Guimarães
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
- Zernike
Institute for Advanced Materials, University
of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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71
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Lyons TP, Gillard D, Molina-Sánchez A, Misra A, Withers F, Keatley PS, Kozikov A, Taniguchi T, Watanabe K, Novoselov KS, Fernández-Rossier J, Tartakovskii AI. Interplay between spin proximity effect and charge-dependent exciton dynamics in MoSe 2/CrBr 3 van der Waals heterostructures. Nat Commun 2020; 11:6021. [PMID: 33244001 PMCID: PMC7691354 DOI: 10.1038/s41467-020-19816-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 10/30/2020] [Indexed: 11/18/2022] Open
Abstract
Semiconducting ferromagnet-nonmagnet interfaces in van der Waals heterostructures present a unique opportunity to investigate magnetic proximity interactions dependent upon a multitude of phenomena including valley and layer pseudospins, moiré periodicity, or exceptionally strong Coulomb binding. Here, we report a charge-state dependency of the magnetic proximity effects between MoSe2 and CrBr3 in photoluminescence, whereby the valley polarization of the MoSe2 trion state conforms closely to the local CrBr3 magnetization, while the neutral exciton state remains insensitive to the ferromagnet. We attribute this to spin-dependent interlayer charge transfer occurring on timescales between the exciton and trion radiative lifetimes. Going further, we uncover by both the magneto-optical Kerr effect and photoluminescence a domain-like spatial topography of contrasting valley polarization, which we infer to be labyrinthine or otherwise highly intricate, with features smaller than 400 nm corresponding to our optical resolution. Our findings offer a unique insight into the interplay between short-lived valley excitons and spin-dependent interlayer tunneling, while also highlighting MoSe2 as a promising candidate to optically interface with exotic spin textures in van der Waals structures.
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Affiliation(s)
- T P Lyons
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK.
| | - D Gillard
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK
| | - A Molina-Sánchez
- QuantaLab, International Iberian Nanotechnology Laboratory, Braga, 4715-330, Portugal
| | - A Misra
- School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK
- Department of Physics, Indian Institute of Technology Madras (IIT Madras), Chennai, India
| | - F Withers
- Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - P S Keatley
- Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - A Kozikov
- School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK
| | - T Taniguchi
- National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - K Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - K S Novoselov
- School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK
- Centre for Advanced 2D Materials, National University of Singapore, Singapore, 117546, Singapore
- Chongqing 2D Materials Institute, Liangjiang New Area, Chongqing, 400714, China
| | - J Fernández-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory, Braga, 4715-330, Portugal
| | - A I Tartakovskii
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK.
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72
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Hwang J, Lee S, Lee JE, Kang M, Ryu H, Joo HJ, Denlinger J, Park JH, Hwang C. Tunable Kondo Resonance at a Pristine Two-Dimensional Dirac Semimetal on a Kondo Insulator. NANO LETTERS 2020; 20:7973-7979. [PMID: 33104350 DOI: 10.1021/acs.nanolett.0c02751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The proximity of two different materials leads to an intricate coupling of quasiparticles so that an unprecedented electronic state is often realized at the interface. Here, we demonstrate a resonance-type many-body ground state in graphene, a nonmagnetic two-dimensional Dirac semimetal, when grown on SmB6, a Kondo insulator, via thermal decomposition of fullerene molecules. This ground state is typically observed in three-dimensional magnetic materials with correlated electrons. Above the characteristic Kondo temperature of the substrate, the electron band structure of pristine graphene remains almost intact. As temperature decreases, however, the Dirac Fermions of graphene become hybridized with the Sm 4f states. Remarkable enhancement of the hybridization and Kondo resonance is observed with further cooling and increasing charge-carrier density of graphene, evidencing the Kondo screening of the Sm 4f local magnetic moment by the conduction electrons of graphene at the interface. These findings manifest the realization of the Kondo effect in graphene by the proximity of SmB6 that is tuned by the temperature and charge-carrier density of graphene.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Seungseok Lee
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Ji-Eun Lee
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Minhee Kang
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Hyun-Jeong Joo
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Jonathan Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jae-Hoon Park
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
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73
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Zollner K, Gmitra M, Fabian J. Swapping Exchange and Spin-Orbit Coupling in 2D van der Waals Heterostructures. PHYSICAL REVIEW LETTERS 2020; 125:196402. [PMID: 33216603 DOI: 10.1103/physrevlett.125.196402] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/24/2020] [Indexed: 06/11/2023]
Abstract
The concept of swapping the two most important spin interactions-exchange and spin-orbit coupling-is proposed based on two-dimensional multilayer van der Waals heterostructures. Specifically, we show by performing realistic ab initio simulations, that a single device consisting of a bilayer graphene sandwiched by a 2D ferromagnet Cr_{2}Ge_{2}Te_{6} (CGT) and a monolayer WS_{2}, is able not only to generate, but also to swap the two interactions. The highly efficient swapping is enabled by the interplay of gate-dependent layer polarization in bilayer graphene and short-range spin-orbit and exchange proximity effects affecting only the layers in contact with the sandwiching materials. We call these structures ex-so-tic, for supplying either exchange (ex) or spin-orbit (so) coupling in a single device, by gating. Such bifunctional devices demonstrate the potential of van der Waals spintronics engineering using 2D crystal multilayers.
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Affiliation(s)
- Klaus Zollner
- Institute for Theoretical Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Martin Gmitra
- Institute of Physics, P. J. Šafárik University in Košice, 04001 Košice, Slovakia
| | - Jaroslav Fabian
- Institute for Theoretical Physics, University of Regensburg, 93053 Regensburg, Germany
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74
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Mukherjee A, Shayan K, Li L, Shan J, Mak KF, Vamivakas AN. Observation of site-controlled localized charged excitons in CrI 3/WSe 2 heterostructures. Nat Commun 2020; 11:5502. [PMID: 33127925 PMCID: PMC7599320 DOI: 10.1038/s41467-020-19262-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/30/2020] [Indexed: 11/09/2022] Open
Abstract
Isolated spins are the focus of intense scientific exploration due to their potential role as qubits for quantum information science. Optical access to single spins, demonstrated in III-V semiconducting quantum dots, has fueled research aimed at realizing quantum networks. More recently, quantum emitters in atomically thin materials such as tungsten diselenide have been demonstrated to host optically addressable single spins by means of electrostatic doping the localized excitons. Electrostatic doping is not the only route to charging localized quantum emitters and another path forward is through band structure engineering using van der Waals heterojunctions. Critical to this second approach is to interface tungsten diselenide with other van der Waals materials with relative band-alignments conducive to the phenomenon of charge transfer. In this work we show that the Type-II band-alignment between tungsten diselenide and chromium triiodide can be exploited to excite localized charged excitons in tungsten diselenide. Leveraging spin-dependent charge transfer in the device, we demonstrate spin selectivity in the preparation of the spin-valley state of localized single holes. Combined with the use of strain-inducing nanopillars to coordinate the spatial location of tungsten diselenide quantum emitters, we uncover the possibility of realizing large-scale deterministic arrays of optically addressable spin-valley holes in a solid state platform.
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Affiliation(s)
- Arunabh Mukherjee
- The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - Kamran Shayan
- The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - Lizhong Li
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
| | - Jie Shan
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.,Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - Kin Fai Mak
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.,Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - A Nick Vamivakas
- The Institute of Optics, University of Rochester, Rochester, NY, USA. .,Materials Science, University of Rochester, Rochester, NY, USA. .,Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA. .,Center for Coherence and Quantum Optics, University of Rochester, Rochester, NY, USA.
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75
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Soriano D, Katsnelson MI, Fernández-Rossier J. Magnetic Two-Dimensional Chromium Trihalides: A Theoretical Perspective. NANO LETTERS 2020; 20:6225-6234. [PMID: 32787171 DOI: 10.1021/acs.nanolett.0c02381] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The discovery of ferromagnetic order in monolayer two-dimensional (2D) crystals has opened a new venue in the field of 2D materials. Two-dimensional magnets are not only interesting on their own, but their integration in van der Waals heterostructures allows for the observation of new and exotic effects in the ultrathin limit. The family of chromium trihalides, CrI3, CrBr3, and CrCl3, is so far the most studied among magnetic 2D crystals. In this Mini Review, we provide a perspective of the state of the art of the theoretical understanding of magnetic 2D trihalides, most of which will also be relevant for other 2D magnets, such as vanadium trihalides. We discuss both the well-established facts, such as the origin of the magnetic moment and magnetic anisotropy, and address as well open issues such as the nature of the anisotropic spin couplings and the magnitude of the magnon gap. Recent theoretical predictions on Moiré magnets and magnetic skyrmions are also discussed. Finally, we give some prospects about the future interest of these materials and possible device applications.
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Affiliation(s)
- D Soriano
- Institute for Molecules and Materials, Radboud University, NL-6525 AJ Nijmegen, The Netherlands
| | - M I Katsnelson
- Institute for Molecules and Materials, Radboud University, NL-6525 AJ Nijmegen, The Netherlands
| | - J Fernández-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenido Mestre José Veiga, 4715-330 Braga, Portugal
- Departamento de Física Aplicada, Universidad de Alicante, 03690, Alicante, Spain
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76
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Zhang D, Liu Y, He M, Zhang A, Chen S, Tong Q, Huang L, Zhou Z, Zheng W, Chen M, Braun K, Meixner AJ, Wang X, Pan A. Room temperature near unity spin polarization in 2D Van der Waals heterostructures. Nat Commun 2020; 11:4442. [PMID: 32895376 PMCID: PMC7477097 DOI: 10.1038/s41467-020-18307-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/28/2020] [Indexed: 11/09/2022] Open
Abstract
The generation and manipulation of spin polarization at room temperature are essential for 2D van der Waals (vdW) materials-based spin-photonic and spintronic applications. However, most of the high degree polarization is achieved at cryogenic temperatures, where the spin-valley polarization lifetime is increased. Here, we report on room temperature high-spin polarization in 2D layers by reducing its carrier lifetime via the construction of vdW heterostructures. A near unity degree of polarization is observed in PbI2 layers with the formation of type-I and type-II band aligned vdW heterostructures with monolayer WS2 and WSe2. We demonstrate that the spin polarization is related to the carrier lifetime and can be manipulated by the layer thickness, temperature, and excitation wavelength. We further elucidate the carrier dynamics and measure the polarization lifetime in these heterostructures. Our work provides a promising approach to achieve room temperature high-spin polarizations, which contribute to spin-photonics applications.
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Affiliation(s)
- Danliang Zhang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Ying Liu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, China
| | - Mai He
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Ao Zhang
- Key Laboratory for Matter Microstructure and Function of Hunan Province, School of Physics and Electronics, Hunan Normal University, Changsha, 410081, China
| | - Shula Chen
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, China
| | - Qingjun Tong
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Lanyu Huang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Zhiyuan Zhou
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Weihao Zheng
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, China
| | - Mingxing Chen
- Key Laboratory for Matter Microstructure and Function of Hunan Province, School of Physics and Electronics, Hunan Normal University, Changsha, 410081, China
| | - Kai Braun
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, Hunan University, Changsha, 410082, China
- Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
| | - Alfred J Meixner
- Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
| | - Xiao Wang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, Hunan University, Changsha, 410082, China.
| | - Anlian Pan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha, 410082, China.
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77
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Lyu B, Gao Y, Zhang Y, Wang L, Wu X, Chen Y, Zhang J, Li G, Huang Q, Zhang N, Chen Y, Mei J, Yan H, Zhao Y, Huang L, Huang M. Probing the Ferromagnetism and Spin Wave Gap in VI 3 by Helicity-Resolved Raman Spectroscopy. NANO LETTERS 2020; 20:6024-6031. [PMID: 32628483 DOI: 10.1021/acs.nanolett.0c02029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Circularly polarized light carries light spin angular momentum, which may lead helicity-resolved Raman scattering to be sensitive to the electronic spin configuration in magnetic materials. Here, we demonstrate that all Raman modes in the 2D ferromagnet VI3 show different scattering intensities to left and right circularly polarized light at low temperatures, which gives direct evidence of the time-reversal symmetry breaking. By measuring the circular polarization of the dominant Raman mode with respect to the temperature and magnetic field, the ferromagnetic (FM) phase transition and hysteresis behavior can be clearly resolved. Besides the lattice excitations, quasielastic scattering is detected in the paramagnetic phase, and it gradually evolves into the acoustic magnon mode at 18.5 cm-1 in the FM state, which gives the spin wave gap that results from large magnetic anisotropy. Our findings demonstrate that helicity-resolved Raman spectroscopy is an effective tool to directly probe the ferromagnetism in 2D magnets.
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Affiliation(s)
- BingBing Lyu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - YiFan Gao
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yujun Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Le Wang
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xiaohua Wu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yani Chen
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jiasheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Gaomin Li
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qiaoling Huang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Naipeng Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuanzhen Chen
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jiawei Mei
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Hugen Yan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yue Zhao
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Li Huang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Mingyuan Huang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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78
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Ciorciaro L, Kroner M, Watanabe K, Taniguchi T, Imamoglu A. Observation of Magnetic Proximity Effect Using Resonant Optical Spectroscopy of an Electrically Tunable MoSe_{2}/CrBr_{3} Heterostructure. PHYSICAL REVIEW LETTERS 2020; 124:197401. [PMID: 32469582 DOI: 10.1103/physrevlett.124.197401] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
van der Waals heterostructures combining two-dimensional magnetic and semiconducting layers constitute a promising platform for interfacing magnetism, electronics, and optics. Here, we use resonant optical reflection spectroscopy to observe the magnetic proximity effect in a gate-tunable MoSe_{2}/CrBr_{3} heterostructure. The high quality of the interface leads to a giant zero-field splitting of the K and K^{'} valley excitons in MoSe_{2}, equivalent to an external magnetic field of 12 T, with a weak but distinct electric field dependence that hints at potential for electrical control of magnetization. The magnetic proximity effect allows us to use resonant optical spectroscopy to fully characterize the CrBr_{3} magnet, determining the easy-axis coercive field, the magnetic anisotropy energy, and critical exponents associated with spin susceptibility and magnetization.
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Affiliation(s)
- Livio Ciorciaro
- Institut für Quantenelektronik, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich, Switzerland
| | - Martin Kroner
- Institut für Quantenelektronik, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich, Switzerland
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Atac Imamoglu
- Institut für Quantenelektronik, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich, Switzerland
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